1. Field of the Invention
The present invention is generally directed toward internal combustion engines and, more specifically, to an internal combustion engine with a cylinder head having a unique head bolt mounting and port arrangements.
2. Description of the Related Art
Internal combustion engines known in the related art may include, among other basic components, a cast engine block having a pair of cylinder banks arranged in a V-shaped configuration, a pair of cylinder heads associated with each cylinder bank mounted to the engine block and a pair of valve covers fastened to each cylinder head. Each bank of cylinders is usually serviced by a dedicated intake manifold mounted to each cylinder head. A plurality of pistons are reciprocated in cylinders formed in each cylinder bank of the engine block. Similarly, a plurality of valves supported in each cylinder head are opened and closed via rocker arms, cams or some other mechanism to provide fluid communication between the cylinders and intake and exhaust manifolds. Fuel is combusted within the cylinders to reciprocate the pistons which, in turn, act on a crankshaft from which power may be translated to drive an automotive vehicle or any number of other devices.
In the case of compression ignition or diesel engines, the fuel/air mixture is delivered at relatively high pressures via fuel injector assemblies. Presently, conventional injectors are delivering this mixture at pressures as high as 32,000 psi. These are fairly high pressures and have required considerable engineering attention to a number of engine components to ensure the structural integrity, good sealing properties and the effective atomization of the fuel within the combustion chamber.
In addition, modern, high speed, direct injection diesel engines often employ cylinder heads having four valves per cylinder to meet challenging performance, noise and emission targets. However, four-valve configurations typically present difficult packaging challenges for small bore, direct injection, diesel engines. As higher engine efficiencies are targeted, engine designers are pushing engines to achieve higher peak firing pressures, necessitating higher head bolt clamp loads. This requirement further complicates the cylinder head and intake port packaging approach.
Many diesel engines adapted for automotive applications in North America will require lower valve train costs to compete effectively with gasoline engines. This factor, among other things, has resulted in the use of an overhead valve (OHV) configuration in the cylinder head, rather than the more generally accepted single overhead camshaft (SOHC) or dual overhead cam shaft (DOHC) design. Especially when employed in connection with V-block engines, overhead valve configurations achieve the necessary automotive diesel-rated speeds with sufficient valve train stiffness, while at the same time resulting in lower overall costs. Further, overhead valve configurations reduce total friction when compared with single or double overhead cam configurations. However, engines which employ overhead valve configurations also require push rods to actuate the valve rocker. Push rods present an additional space claim in the already crowded cylinder head envelope.
In essence, then, the modern diesel engine must provide a substantial fuel economy advantage while meeting evermore stringent emission regulations which are imposed on smaller, more compact diesel engines. However, increasing demands for greater fuel economy, cleaner burning, fewer emissions, NO.sub.x and noise control in addition to better component packaging, have placed, and will continue to place, even higher demands on the engine. Thus, there is an ongoing need in the art for better control over these various parameters in a cost-effective manner.